ANTIOXIDANT ACTIVITY OF PHYTOESTROGENIC ISOFLAVONES

The aim of this work was to determine the antioxidant activities of a range of phytoestrogenic isoflavones. The antioxidant activity in the aqueous phase was determined by means of the ABTS(.+) total antioxidan t activity assay. The results show that the order of reactivity in sca venging the radical in the aqueous phase is genistein > daidzein = gen istin approximate to biochanin A = daidzin > formononetin approximate to ononin, the latter displaying no antioxidant activity. The importan ce of the single 4'-hydroxyl group in the reactivity of the isoflavone s, as scavengers of aqueous phase radicals, as well as the 5,7-dihydro xy structure is demonstrated. Examination of their abilities to enhanc e the resistance of low density lipoproteins to oxidation supports the observation that genistein is the most potent antioxidant among this family of compounds studied, both in the aqueous and in the lipophilic phases.